Distant, ancient galaxies are giving scientists more hints that a mysterious force called dark energy may not be what they thought.
Astronomers know that the universe is being pushed apart at an accelerating rate and they have puzzled for decades over what could possibly be speeding everything up. They theorize that a powerful, constant force is at play, one that fits nicely with the main mathematical model that describes how the universe behaves. But they can't see it and they don't know where it comes from, so they call it dark energy.
It is so vast it is thought to make up nearly 70 of the universe - while ordinary matter like all the stars and planets and people make up just 5.
But findings published earlier this year by an international research collaboration of more than 900 scientists from around the globe yielded a major surprise. As the scientists analyzed how galaxies move they found that the force pushing or pulling them around did not seem to be constant. And the same group published a new, broader set of analyses Tuesday that yielded a similar answer.
"I did not think that such a result would happen in my lifetime," said Mustapha Ishak-Boushaki, a cosmologist at the University of Texas at Dallas who is part of the collaboration.
